Influence of temperature and relative humidity on vapor hydration of an AVM nuclear waste glass

Borosilicate glass alteration in vapor phase and aqueous medium

“…By closely observing the ToF-SIMS profiles in our previous studies, a similar combined enrichment of Na + and H + has been observed in some cases 27,31,37 .…”

“…Surprisingly, the gel layer thickness measured using ToF-SIMS does not correspond with the thickness measured through SEM images. In literature, a good correspondence between gel layer thickness measured between SEM and ToF-SIMS has been frequently reported 27,[29][30][31] , which makes the discrepancy in our study enigmatic. The following hypothesis could be considered, although it is not verifiable for these samples.…”

“…In many vapor hydration studies, boron is the element that is the most depleted in the altered layer (in depth and in quantity) 25,27,29,31,37,50 . Retention of boron in the gel layer is often less than 10-20%.…”

“…Some of these experimental data have been useful to develop geochemical, empirical or structure-based models to predict glass alteration rates, at least during specific alteration stages [18][19][20][21][22][23][24] . On the other hand, the studies investigating nuclear waste glass alteration in humid conditions (referred to as vapor hydration or vapor phase alteration) are relatively fewer [25][26][27][28][29][30][31][32] . A generalized understanding of the predominant glass alteration mechanisms in the vapor phase is yet to be achieved.…”

Forty years of durability assessment of nuclear waste glass by standard methods

“…It was first published by PNNL in 1999 and accepted in 2009 as ASTM C1663 Standard Test Method for Measuring Waste Glass or Glass Ceramic Durability by Vapour Hydration Test 88,89 . An almost identical method [90][91][92] controls the relative humidity within the experimental system using a saline solution and allows a VHT-like test to be performed at lower temperatures representing dissolution by water vapour rather than liquid water. In the ASTM C1663 VHT method polished glass coupons (medium polish 30 micron) are suspended by a platinum wire holder in a sealed stainless steel containment vessel, which is then subjected to temperatures of up to 200 °C for a standard duration of 28 days though shorter or longer durations are possible (Fig.…”